Abstract
Abstract. On 1 October 2009, a prolonged and intense rainstorm triggered hundreds of landslides (predominantly debris flows) in an area of about 50 km2 in the north-eastern sector of Sicily (Italy). Debris flows swept the highest parts of many villages and passed over the SS114 state highway and the Messina-Catania railway, causing more than 30 fatalities. This region has a high relief, due to recent uplift. The peculiar geological and geomorphological framework represents one of the most common predisposing causes of rainstorm-triggered debris flows. This paper deals with the geological and hydro-geomorphological studies performed as a part of the post-disaster activities operated in collaboration with Civil Protection Authority, with the aim at examining landslides effects and mechanisms. The data were elaborated into a GIS platform, to evaluate the influence of urbanisation on the drainage pattern, and were correlated with the lithological and structural framework of the area. Our study points at the evaluation of the volume involved, the detection of triggering mechanisms and the precise reconstruction of the influence of urbanisation as fundamental tools for understanding the dynamics of catastrophic landslides. This kind of analysis, including all the desirable approaches for the correct management of debris flow should be the starting point for robust urban planning.
Highlights
Landslides are one of the most important geological hazards and are responsible for substantial human and economic losses
We present the results obtained by different methodologies (i.e., geological and geomorphological mapping, digital elevation model (DEM) analysis, debris flow intensity index (DSI)) that could be a useful tool to develop a proper urban planning in areas subjected to debris flows hazard
The results obtained from the different methodologies described above were integrated in a GIS environment to evaluate the tendency of landslides occurrence in the Giampilieri area
Summary
Landslides are one of the most important geological hazards and are responsible for substantial human and economic losses. Following Hungr et al (2001), the key characteristics of debris flows are: (1) presence of an established channel or a regular confined path; (2) a certain degree of rough sorting of the involved material, which tends to move the largest boulders towards the flow surface This process produces a longitudinal sorting and the gathering of boulders near the front, increasing the destructive potential of the slide (Pierson, 1986); (3) complete saturation: the water content can be highly variable depending on the heterogeneity of debris flow surges and varies temporally, as a result of the gradual dilution of the mass as it progresses downstream (Iverson, 1997). A hydrometeorological event which is intense enough to saturate the soil and to induce sufficient pore-water pressure, occurring in an area characterised by loose materials on steep slopes, can trigger debris flows (Zimmermann and Haeberli, 1992; Pierson et al, 1990; O’Connor et al, 1997; Johnson, 1984; Iverson, 1997). We present the results obtained by different methodologies (i.e., geological and geomorphological mapping, DEM analysis, debris flow intensity index (DSI)) that could be a useful tool to develop a proper urban planning in areas subjected to debris flows hazard
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